Biomolecules 2017, 7(1), 12; doi:10.3390/biom7010012
The Escherichia coli COG1738 Member YhhQ Is Involved in 7-Cyanodeazaguanine (preQ0) Transport
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA
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Academic Editor: Jürg Bähler
Received: 22 December 2016 / Revised: 27 January 2017 / Accepted: 30 January 2017 / Published: 8 February 2017
(This article belongs to the Special Issue tRNA Modifications: Synthesis, Function and Beyond)
Abstract
Queuosine (Q) is a complex modification of the wobble base in tRNAs with GUN anticodons. The full Q biosynthesis pathway has been elucidated in Escherichia coli. FolE, QueD, QueE and QueC are involved in the conversion of guanosine triphosphate (GTP) to 7-cyano-7-deazaguanine (preQ0), an intermediate of increasing interest for its central role in tRNA and DNA modification and secondary metabolism. QueF then reduces preQ0 to 7-aminomethyl-7-deazaguanine (preQ1). PreQ1 is inserted into tRNAs by tRNA guanine(34) transglycosylase (TGT). The inserted base preQ1 is finally matured to Q by two additional steps involving QueA and QueG or QueH. Most Eubacteria harbor the full set of Q synthesis genes and are predicted to synthesize Q de novo. However, some bacteria only encode enzymes involved in the second half of the pathway downstream of preQ0 synthesis, including the signature enzyme TGT. Different patterns of distribution of the queF, tgt, queA and queG or queH genes are observed, suggesting preQ0, preQ1 or even the queuine base being salvaged in specific organisms. Such salvage pathways require the existence of specific 7-deazapurine transporters that have yet to be identified. The COG1738 family was identified as a candidate for a missing preQ0/preQ1 transporter in prokaryotes, by comparative genomics analyses. The existence of Q precursor salvage was confirmed for the first time in bacteria, in vivo, through an indirect assay. The involvement of the COG1738 in salvage of a Q precursor was experimentally validated in Escherichia coli, where it was shown that the COG1738 family member YhhQ is essential for preQ0 transport. View Full-TextKeywords:
7-deazapurine; queuosine; preQ0; preQ1; queuine; tRNA modification; transport; salvage; COG1738; ECF-type ATP-binding cassette
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Zallot, R.; Yuan, Y.; de Crécy-Lagard, V. The Escherichia coli COG1738 Member YhhQ Is Involved in 7-Cyanodeazaguanine (preQ0) Transport. Biomolecules 2017, 7, 12.
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